Southern Pine Beetle in Loblolly Pine: Simulating within Stand Interactions Using the Process Model Spblobthin

Pine stand density is a key determinant of damage resulting from attacks by the southern pine beetle (SPB, Dendroctonus frontalis Zimm.). High-density stands of maturing loblolly pine (Pinus taeda L.) are at high risk for losses to SPB, and reducing stand density is the primary tool available to forest managers for preventing and mitigating damage. Field studies are expensive and inflexible for evaluating various stand treatments over large areas and long time periods, especially with unpredictable SPB population levels. To address these shortcomings, and to provide guidance on silvicultural treatment selection for future field studies, we have developed a process model (SPBLOBTHIN) to simulate the joint population dynamics of loblolly pine and SPB in single stands. Our model grows and tracks individual trees and beetles, both temporally and spatially, and includes stochasticity where desired. The model allows great flexibility in assigning values to input parameters, including those that designate temperature, site index, tree resistance, stand density, and thinning regime. We have also linked model output values to the U.S. Department of Agriculture, Forest Service’s Stand Visualization System (SVS), an existing tool for producing realistic and useful views of stand and tree characteristics over time. The objectives of this report are to highlight the flexibility and utility of SPBLOBTHIN, present output created by its linkage with SVS, and compare model simulation results with those obtained in an earlier field study from which pest management thinning recommendations were developed for loblolly pine.